Re: Exposing FUA as alternative to DIOCCACHESYNC for WAPBL

[<Paul.Koning%dell.com@localhost>]

> On Mar 31, 2017, at 4:16 PM, Thor Lancelot Simon <tls%panix.com@localhost> wrote:
> 
> On Fri, Mar 31, 2017 at 07:16:25PM +0200, Jarom??r Dole??ek wrote:
>>> The problem is that it does not always use SIMPLE and ORDERED tags in a
>>> way that would facilitate the use of ORDERED tags to enforce barriers.
>> 
>> Our scsipi layer actually never issues ORDERED tags right now as far
>> as I can see, and there is currently no interface to get it set for an
>> I/O.
> 
> It's not obvious, but in fact ORDERED gets set for writes
> as a default, I believe -- in sd.c, I think?

Why would you do that?  I don't know that as standard SCSI practice, and it seems like a recipe for slow performance.

	paul